Answer: 5¹ + 5² + 5³, 130 students
Step-by-step explanation:
Monday: 1 1 1 1 1 = 5 ⇒ 5¹
+ Tuesday: 1(5) 1(5) 1(5) 1(5) 1(5) = + 25 ⇒ 5²
+ Wednesday:5(5) 5(5) 5(5) 5(5) 5(5) = +125 ⇒ 5³
130
Extra Credit: How many students will know the rumor on Thursday? 5¹ + 5² + 5³ + 5⁴